- A PC with external speakers, one speaker having a headphone output:
- A stereo jack plug soldered to a few centimeters of wire
- This great online tone generator software at https://www.szynalski.com/tone-generator/
Saw Tooth wave
Adjust the frequency to the RPM you want: ie 50Hz x 60 = 3000RPM
Adjust the voltage with the volume potentiometer.
Here are 4 snapshots of the different wave form signals at 50Hz with volume settings at max: